The present invention relates to an air damper for control of the flow air, for example, between compartments of a refrigerator, and in particular to an improved air damper with linear valve travel and a low cost electric actuator.
A household refrigerator may provide for a number of different compartments with different temperature and humidity conditions. A convenient method of creating these multiple environments employs one or more dampers controlling the flow of air flow between the compartments.
Dampers of this type may use a pivoting door or flapper that is opened and closed by a motor or other actuator. The actuators are normally limited to relatively low wattage devices, for example, low voltage DC motors, to reduce cost, promote energy efficiency, and to minimize heat dissipation by the actuator within the refrigerator.
The operating environment of the dampers, positioned between chambers with different air temperatures and humidities, can produce condensation and icing on the damper components. Ice can interfere with the pivoting action of the flapper by encrusting the pivot point of the flapper or by causing adhesion between the outboard portion of the flapper and the rim of the damper opening where small amounts or resistance can require large torques to overcome.
In order to eliminate leakage around the flapper, the flapper may include a gasket compressed between the flapper and the damper opening. This gasket is often a highly compliant foam material sealing with low compression forces. The foam gasket accommodates the varying forces, and possibly varying separation, between the flapper and damper opening caused by the pivoting action of the flapper.
A drawback to foam gaskets is that they may absorb water, freeze, and become less compliant or adhered to the damper opening, as described above. Further, foam gaskets may become brittle with time losing their compliance and sealing ability.